1
|
Glöckner N, zur Oven-Krockhaus S, Rohr L, Wackenhut F, Burmeister M, Wanke F, Holzwart E, Meixner AJ, Wolf S, Harter K. Three-Fluorophore FRET Enables the Analysis of Ternary Protein Association in Living Plant Cells. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11192630. [PMID: 36235497 PMCID: PMC9571070 DOI: 10.3390/plants11192630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 09/19/2022] [Accepted: 09/24/2022] [Indexed: 05/13/2023]
Abstract
Protein-protein interaction studies provide valuable insights into cellular signaling. Brassinosteroid (BR) signaling is initiated by the hormone-binding receptor Brassinosteroid Insensitive 1 (BRI1) and its co-receptor BRI1 Associated Kinase 1 (BAK1). BRI1 and BAK1 were shown to interact independently with the Receptor-Like Protein 44 (RLP44), which is implicated in BRI1/BAK1-dependent cell wall integrity perception. To demonstrate the proposed complex formation of BRI1, BAK1 and RLP44, we established three-fluorophore intensity-based spectral Förster resonance energy transfer (FRET) and FRET-fluorescence lifetime imaging microscopy (FLIM) for living plant cells. Our evidence indicates that RLP44, BRI1 and BAK1 form a ternary complex in a distinct plasma membrane nanodomain. In contrast, although the immune receptor Flagellin Sensing 2 (FLS2) also forms a heteromer with BAK1, the FLS2/BAK1 complexes are localized to other nanodomains. In conclusion, both three-fluorophore FRET approaches provide a feasible basis for studying the in vivo interaction and sub-compartmentalization of proteins in great detail.
Collapse
Affiliation(s)
- Nina Glöckner
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72076 Tübingen, Germany
| | - Sven zur Oven-Krockhaus
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72076 Tübingen, Germany
- Institute for Physical & Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Leander Rohr
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72076 Tübingen, Germany
| | - Frank Wackenhut
- Institute for Physical & Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Moritz Burmeister
- Institute for Physical & Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Friederike Wanke
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72076 Tübingen, Germany
| | - Eleonore Holzwart
- Centre for Organismal Studies (COS), University of Heidelberg, 69117 Heidelberg, Germany
| | - Alfred J. Meixner
- Institute for Physical & Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Sebastian Wolf
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72076 Tübingen, Germany
- Centre for Organismal Studies (COS), University of Heidelberg, 69117 Heidelberg, Germany
| | - Klaus Harter
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72076 Tübingen, Germany
- Correspondence: ; Tel.: +49-(0)-7071-2972605
| |
Collapse
|
2
|
Ni Z, Gale A, Johnson MS, Sedger LM. Analysis insights for three FRET pairs of chemically unlinked two-molecule FRET cytometry. Cytometry A 2021; 101:387-399. [PMID: 34935263 DOI: 10.1002/cyto.a.24527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/21/2021] [Accepted: 12/06/2021] [Indexed: 11/07/2022]
Abstract
Förster resonance energy transfer (FRET) is the direct energy exchange between two-component fluorescent molecules. FRET methods utilize chemically linked molecules or unlinked fluorescence protein-protein interactions. FRET is therefore a powerful indicator of molecular proximity, but standardized determination of FRET efficiency is challenged when investigating natural (chemically unlinked) interactions. In this paper, we have examined the interactions of tumor necrosis factor receptor-1 (TNFR1) molecules expressed as recombinant fusion proteins of cyan, yellow, or red fluorescent protein (-CFP, -YFP, or -RFP) to evaluate two-molecule chemically unlinked FRET by flow cytometry. We demonstrate three independent FRET pairs CFP→YFP (FRET-1), YFP→RFP (FRET-2) and CFP→RFP (FRET-3), comparing TNFR1+TNFR1 with non-interacting TNFR1+CD27 proteins, on both LSR-II and Fortessa X-20 cytometers. We describe genuine FRET activities reflecting TNFR1 homotypic interactions. FRET events can be visualized during sample acquisition via the use of "spiked" FRET donor cells, together with TNFR1+TNFR1 co-transfected cells, as FRET channel MFI overlays. FRET events are subsequentially indicated by comparing concatenated files of cells expressing either FRET positive events (TNFR1+TNFR1) or FRET negative events (TNFR1+CD27) to generate single-cell scatter plots showing loss of FRET donor brightness. Robust determination of FRET efficiency is then confirmed at the single-cell level by applying matrix calculations based on the measurements of FRET donor, acceptor and FRET fluorescent intensities (I), detector channel emission coefficient (S), fluorescent protein extinction coefficients (ε) and α factor. In this TNFR based system, the mean CFP→YFP FRET-1 efficiency is 0.43 (LSR-II) and 0.41 (Fortessa), the mean YFP→RFP FRET-2 efficiency is 0.30 (LSR-II) and 0.29 (Fortessa), and the mean CFP→RFP FRET-3 efficiency is 0.56 (LSR-II) and 0.54 (Fortessa). This study also embraces multidimensional clustering using t-SNE, Fit-SNE, UMAP, Tri-Map and PaCMAP to further demonstrate FRET. These approaches establish a robust system for standardized detection of chemically unlinked TNFR1 homotypic interactions with three individual FRET pairs.
Collapse
Affiliation(s)
- Zhongran Ni
- School of Life Science, Faculty of Science, University of Technology Sydney
| | - Alex Gale
- School of Life Science, Faculty of Science, University of Technology Sydney
| | - Michael S Johnson
- School of Life Science, Faculty of Science, University of Technology Sydney
| | - Lisa M Sedger
- School of Life Science, Faculty of Science, University of Technology Sydney
| |
Collapse
|
3
|
Excitation polarization angle-resolved single-laser dual-polarization energy transfer on the cell surface. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2021.113519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
4
|
Eckenstaler R, Benndorf RA. A Combined Acceptor Photobleaching and Donor Fluorescence Lifetime Imaging Microscopy Approach to Analyze Multi-Protein Interactions in Living Cells. Front Mol Biosci 2021; 8:635548. [PMID: 34055873 PMCID: PMC8160235 DOI: 10.3389/fmolb.2021.635548] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 04/19/2021] [Indexed: 11/13/2022] Open
Abstract
Protein-protein interaction studies often provide new insights, i.e., into the formation of protein complexes relevant for structural oligomerization, regulation of enzymatic activity or information transfer within signal transduction pathways. Mostly, biochemical approaches have been used to study such interactions, but their results are limited to observations from lysed cells. A powerful tool for the non-invasive investigation of protein-protein interactions in the context of living cells is the microscopic analysis of Förster Resonance Energy Transfer (FRET) among fluorescent proteins. Normally, FRET is used to monitor the interaction state of two proteins, but in addition, FRET studies have been used to investigate three or more interacting proteins at the same time. Here we describe a fluorescence microscopy-based method which applies a novel 2-step acceptor photobleaching protocol to discriminate between non-interacting, dimeric interacting and trimeric interacting states within a three-fluorophore setup. For this purpose, intensity- and fluorescence lifetime-related FRET effects were analyzed on representative fluorescent dimeric and trimeric FRET-constructs expressed in the cytosol of HEK293 cells. In particular, by combining FLIM- and intensity-based FRET data acquisition and interpretation, our method allows to distinguish trimeric from different types of dimeric (single-, double- or triple-dimeric) protein-protein interactions of three potential interaction partners in the physiological setting of living cells.
Collapse
Affiliation(s)
- Robert Eckenstaler
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Ralf A Benndorf
- Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| |
Collapse
|
5
|
Szabó Á, Szendi-Szatmári T, Szöllősi J, Nagy P. Quo vadis FRET? Förster's method in the era of superresolution. Methods Appl Fluoresc 2020; 8:032003. [PMID: 32521530 DOI: 10.1088/2050-6120/ab9b72] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Although the theoretical foundations of Förster resonance energy transfer (FRET) were laid in the 1940s as part of the quantum physical revolution of the 20th century, it was only in the 1970s that it made its way to biology as a result of the availability of suitable measuring and labeling technologies. Thanks to its ease of application, FRET became widely used for studying molecular associations on the nanometer scale. The development of superresolution techniques at the turn of the millennium promised an unprecedented insight into the structure and function of molecular complexes. Without downplaying the significance of superresolution microscopies this review expresses our view that FRET is still a legitimate tool in the armamentarium of biologists for studying molecular associations since it offers distinct advantages and overcomes certain limitations of superresolution approaches.
Collapse
Affiliation(s)
- Ágnes Szabó
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem square 1, 4032 Debrecen, Hungary. MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem square 1, 4032 Debrecen, Hungary
| | | | | | | |
Collapse
|
6
|
Hochreiter B, Kunze M, Moser B, Schmid JA. Advanced FRET normalization allows quantitative analysis of protein interactions including stoichiometries and relative affinities in living cells. Sci Rep 2019; 9:8233. [PMID: 31160659 PMCID: PMC6547726 DOI: 10.1038/s41598-019-44650-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 05/20/2019] [Indexed: 12/31/2022] Open
Abstract
FRET (Fluorescence Resonance Energy Transfer) measurements are commonly applied to proof protein-protein interactions. However, standard methods of live cell FRET microscopy and signal normalization only allow a principle assessment of mutual binding and are unable to deduce quantitative information of the interaction. We present an evaluation and normalization procedure for 3-filter FRET measurements, which reflects the process of complex formation by plotting FRET-saturation curves. The advantage of this approach relative to traditional signal normalizations is demonstrated by mathematical simulations. Thereby, we also identify the contribution of critical parameters such as the total amount of donor and acceptor molecules and their molar ratio. When combined with a fitting procedure, this normalization facilitates the extraction of key properties of protein complexes such as the interaction stoichiometry or the apparent affinity of the binding partners. Finally, the feasibility of our method is verified by investigating three exemplary protein complexes. Altogether, our approach offers a novel method for a quantitative analysis of protein interactions by 3-filter FRET microscopy, as well as flow cytometry. To facilitate the application of this method, we created macros and routines for the programs ImageJ, R and MS-Excel, which we make publicly available.
Collapse
Affiliation(s)
- Bernhard Hochreiter
- Medical University Vienna, Center for Physiology and Pharmacology, Institute for Vascular Biology and Thrombosis Research, Vienna, Austria
| | - Markus Kunze
- Medical University Vienna, Center for Brain Research, Department of Pathobiology of the Nervous System, Vienna, Austria
| | - Bernhard Moser
- Medical University Vienna, Center for Physiology and Pharmacology, Institute for Vascular Biology and Thrombosis Research, Vienna, Austria
| | - Johannes A Schmid
- Medical University Vienna, Center for Physiology and Pharmacology, Institute for Vascular Biology and Thrombosis Research, Vienna, Austria.
| |
Collapse
|
7
|
Dagher M, Kleinman M, Ng A, Juncker D. Ensemble multicolour FRET model enables barcoding at extreme FRET levels. NATURE NANOTECHNOLOGY 2018; 13:925-932. [PMID: 30061659 DOI: 10.1038/s41565-018-0205-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 06/17/2018] [Indexed: 05/02/2023]
Abstract
Quantitative models of Förster resonance energy transfer (FRET)-pioneered by Förster-define our understanding of FRET and underpin its widespread use. However, multicolour FRET (mFRET), which arises between multiple, stochastically distributed fluorophores, lacks a mechanistic model and remains intractable. mFRET notably arises in fluorescently barcoded microparticles, resulting in a complex, non-orthogonal fluorescence response that impedes their encoding and decoding. Here, we introduce an ensemble mFRET (emFRET) model, and apply it to guide barcoding into regimes with extreme FRET. We further introduce a facile, proportional multicolour labelling method using oligonucleotides as homogeneous linkers. A total of 580 barcodes were rapidly designed and validated using four dyes-with FRET efficiencies reaching 76%-and used for multiplexed immunoassays with cytometric readout and fully automated decoding. The emFRET model helps to expand the barcoding capacity of barcoded microparticles using common organic dyes and will benefit other applications subject to stochastic mFRET.
Collapse
Affiliation(s)
- Milad Dagher
- Biomedical Engineering Department, McGill University, Montreal, Quebec, Canada
- McGill University and Genome Quebec Innovation Center, Montreal, Quebec, Canada
| | - Michael Kleinman
- Biomedical Engineering Department, McGill University, Montreal, Quebec, Canada
- McGill University and Genome Quebec Innovation Center, Montreal, Quebec, Canada
| | - Andy Ng
- Biomedical Engineering Department, McGill University, Montreal, Quebec, Canada
- McGill University and Genome Quebec Innovation Center, Montreal, Quebec, Canada
| | - David Juncker
- Biomedical Engineering Department, McGill University, Montreal, Quebec, Canada.
- McGill University and Genome Quebec Innovation Center, Montreal, Quebec, Canada.
- Neurology and Neurosurgery Department, McGill University, Montreal, Quebec, Canada.
| |
Collapse
|
8
|
Bene L, Bagdány M, Ungvári T, Damjanovich L. Dual-Laser Tetra-Polarization FRET (4polFRET) for Site-Selective Control of Homo-FRET in Hetero-FRET Systems on the Cell Surface: The Homo-FRET Gate. Anal Chem 2018; 90:10159-10170. [DOI: 10.1021/acs.analchem.7b05441] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- László Bene
- Department of Surgery, Faculty of Medicine, University of Debrecen P.O. Box 400, Debrecen H-4002, Hungary
| | - Miklós Bagdány
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal H3G1Y6, Canada
| | - Tamás Ungvári
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, P.O. Box 400, Debrecen H-4002, Hungary
| | - László Damjanovich
- Department of Surgery, Faculty of Medicine, University of Debrecen P.O. Box 400, Debrecen H-4002, Hungary
| |
Collapse
|
9
|
de Ruiter MV, Overeem NJ, Singhai G, Cornelissen JJLM. Induced Förster resonance energy transfer by encapsulation of DNA-scaffold based probes inside a plant virus based protein cage. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:184002. [PMID: 29512513 PMCID: PMC7104908 DOI: 10.1088/1361-648x/aab4a9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 02/16/2018] [Accepted: 03/07/2018] [Indexed: 06/08/2023]
Abstract
Insight into the assembly and disassembly of viruses can play a crucial role in developing cures for viral diseases. Specialized fluorescent probes can benefit the study of interactions within viruses, especially during cell studies. In this work, we developed a strategy based on Förster resonance energy transfer (FRET) to study the assembly of viruses without labeling the exterior of viruses. Instead, we exploit their encapsulation of nucleic cargo, using three different fluorescent ATTO dyes linked to single-stranded DNA oligomers, which are hybridised to a longer DNA strand. FRET is induced upon assembly of the cowpea chlorotic mottle virus, which forms monodisperse icosahedral particles of about 22 nm, thereby increasing the FRET efficiency by a factor of 8. Additionally, encapsulation of the dyes in virus-like particles induces a two-step FRET. When the formed constructs are disassembled, this FRET signal is fully reduced to the value before encapsulation. This reversible behavior makes the system a good probe for studying viral assembly and disassembly. It, furthermore, shows that multi-component supramolecular materials are stabilized in the confinement of a protein cage.
Collapse
Affiliation(s)
- Mark V de Ruiter
- Laboratory of Biomolecular Nanotechnology, MESA + Institute of Nanotechnology, University of Twente, P O Box 217, 7500 AE, Enschede, Netherlands
| | - Nico J Overeem
- Laboratory of Biomolecular Nanotechnology, MESA + Institute of Nanotechnology, University of Twente, P O Box 217, 7500 AE, Enschede, Netherlands
| | - Gaurav Singhai
- Laboratory of Biomolecular Nanotechnology, MESA + Institute of Nanotechnology, University of Twente, P O Box 217, 7500 AE, Enschede, Netherlands
- Flinders Centre for Nanoscale Science and Technology, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - Jeroen J L M Cornelissen
- Laboratory of Biomolecular Nanotechnology, MESA + Institute of Nanotechnology, University of Twente, P O Box 217, 7500 AE, Enschede, Netherlands
| |
Collapse
|
10
|
Bag SS, Yashmeen A. A relay FRET event in a designed trichromophoric pentapeptide containing an o-, m-aromatic-amino acid scaffold. Chem Commun (Camb) 2018; 54:9765-9768. [DOI: 10.1039/c8cc04429e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The concept of a relay FRET event is established in a designed trichromophoric pentapeptide containing an o-,m-aromatic amino acid scaffold in the backbone as a novel β-turn mimetic β-sheet folding nucleator.
Collapse
Affiliation(s)
- Subhendu Sekhar Bag
- Bioorganic Chemistry Laboratory
- Department of Chemistry
- Indian Institute of Technology Guwahati
- North Guwahati-781039
- India
| | - Afsana Yashmeen
- Bioorganic Chemistry Laboratory
- Department of Chemistry
- Indian Institute of Technology Guwahati
- North Guwahati-781039
- India
| |
Collapse
|
11
|
Abstract
In the past decades, investigation of protein-protein interactions in situ in living or intact cells has gained expanding importance as structure/function relationships proposed from bulk biochemistry and molecular modeling experiments required confirmation at the cellular level. Förster (fluorescence) resonance energy transfer (FRET)-based methods are excellent tools for determining proximity and supramolecular organization of biomolecules at the cell surface or inside the cell. This could well be the basis for the increasing popularity of FRET. In fact, the number of publications exploiting FRET has exploded since the turn of the millennium. Interestingly, most applications are microscope-based, and only a fraction employs flow cytometry, even though the latter offers great statistical power owed to the potentially huge number of individually measured cells. However, with the increased availability of multi-laser flow cytometers, strategies to obtain absolute FRET efficiencies can now be relatively facilely implemented. In this chapter, we intend to provide generally useable protocols for measuring FRET in flow cytometry. After a concise theoretical introduction, recipes are provided for successful labeling techniques and measurement approaches. The simple, quenching-based population-level measurement, the classic ratiometric, intensity-based technique providing cell-by-cell actual FRET efficiencies, and a more advanced version of the latter, allowing for cell-by-cell autofluorescence correction are described. An Excel macro pre-loaded with spectral data of the most commonly used fluorophores is also provided for easy calculation of average FRET efficiencies. Finally, points of caution are given to help design proper experiments and critically interpret the results.
Collapse
Affiliation(s)
- László Ujlaky-Nagy
- Department of Biophysics and Cell Biology, MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter Nagy
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - János Szöllősi
- Department of Biophysics and Cell Biology, MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - György Vereb
- Department of Biophysics and Cell Biology, MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, Faculty of Pharmacy, University of Debrecen, Debrecen, Hungary.
| |
Collapse
|
12
|
Szöllősi J, Vereb G, Nagy P. The flow of events: How the sequence of molecular interactions is seen by the latest, user-friendly high throughput flow cytometric FRET. Cytometry A 2016; 89:881-885. [DOI: 10.1002/cyto.a.22994] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 09/12/2016] [Accepted: 09/15/2016] [Indexed: 12/22/2022]
Affiliation(s)
- János Szöllősi
- Department of Biophysics and Cell Biology, Faculty of Medicine; University of Debrecen; Debrecen Hungary
- MTA-DE Cell Biology and Signaling Research Group, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen; Debrecen Hungary
| | - György Vereb
- Department of Biophysics and Cell Biology, Faculty of Medicine; University of Debrecen; Debrecen Hungary
| | - Péter Nagy
- Department of Biophysics and Cell Biology, Faculty of Medicine; University of Debrecen; Debrecen Hungary
| |
Collapse
|
13
|
Horvath GL, Langhoff P, Latz E. Toll-Like Receptor Interactions Measured by Microscopic and Flow Cytometric FRET. Methods Mol Biol 2016; 1390:41-64. [PMID: 26803621 DOI: 10.1007/978-1-4939-3335-8_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Protein-protein interactions regulate biological networks. The most proximal events that initiate signal transduction frequently are receptor dimerization or conformational changes in receptor complexes. Toll-like receptors (TLRs) are transmembrane receptors that are activated by a number of exogenous and endogenous ligands. Most TLRs can respond to multiple ligands and the different TLRs recognize structurally diverse molecules ranging from proteins, sugars, lipids, and nucleic acids. TLRs can be expressed on the plasma membrane or in endosomal compartments and ligand recognition thus proceeds in different microenvironments. Not surprisingly, distinctive mechanisms of TLR receptor activation have evolved. A detailed understanding of the mechanisms of TLR activation is important for the development of novel synthetic TLR activators or pharmacological inhibitors of TLRs. Confocal laser scanning microscopy combined with GFP technology allows the direct visualization of TLR expression in living cells. Fluorescence resonance energy transfer (FRET) measurements between two differentially tagged proteins permit the study of TLR interaction, and distances between receptors in the range of molecular interactions can be measured and visualized. Additionally, FRET measurements combined with confocal microscopy provide detailed information about molecular interactions in different subcellular localizations. These techniques permit the dynamic visualization of early signaling events in living cells and can be utilized in pharmacological or genetic screens.
Collapse
Affiliation(s)
- Gabor L Horvath
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany
| | - Pia Langhoff
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany
| | - Eicke Latz
- Institute of Innate Immunity, University Hospitals, University of Bonn, 53127, Bonn, Germany.
- University of Massachusetts Medical School, Worcester, MA, 01605, USA.
| |
Collapse
|
14
|
Shrestha D, Jenei A, Nagy P, Vereb G, Szöllősi J. Understanding FRET as a research tool for cellular studies. Int J Mol Sci 2015; 16:6718-56. [PMID: 25815593 PMCID: PMC4424985 DOI: 10.3390/ijms16046718] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/18/2015] [Indexed: 01/06/2023] Open
Abstract
Communication of molecular species through dynamic association and/or dissociation at various cellular sites governs biological functions. Understanding these physiological processes require delineation of molecular events occurring at the level of individual complexes in a living cell. Among the few non-invasive approaches with nanometer resolution are methods based on Förster Resonance Energy Transfer (FRET). FRET is effective at a distance of 1-10 nm which is equivalent to the size of macromolecules, thus providing an unprecedented level of detail on molecular interactions. The emergence of fluorescent proteins and SNAP- and CLIP- tag proteins provided FRET with the capability to monitor changes in a molecular complex in real-time making it possible to establish the functional significance of the studied molecules in a native environment. Now, FRET is widely used in biological sciences, including the field of proteomics, signal transduction, diagnostics and drug development to address questions almost unimaginable with biochemical methods and conventional microscopies. However, the underlying physics of FRET often scares biologists. Therefore, in this review, our goal is to introduce FRET to non-physicists in a lucid manner. We will also discuss our contributions to various FRET methodologies based on microscopy and flow cytometry, while describing its application for determining the molecular heterogeneity of the plasma membrane in various cell types.
Collapse
Affiliation(s)
- Dilip Shrestha
- Department of Biophysics and Cell Biology, University of Debrecen, Egyetem tér 1, Nagyerdei Krt. 98, Debrecen 4032, Hungary.
- MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen 4032, Hungary.
| | - Attila Jenei
- Department of Biophysics and Cell Biology, University of Debrecen, Egyetem tér 1, Nagyerdei Krt. 98, Debrecen 4032, Hungary.
| | - Péter Nagy
- Department of Biophysics and Cell Biology, University of Debrecen, Egyetem tér 1, Nagyerdei Krt. 98, Debrecen 4032, Hungary.
| | - György Vereb
- Department of Biophysics and Cell Biology, University of Debrecen, Egyetem tér 1, Nagyerdei Krt. 98, Debrecen 4032, Hungary.
- MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen 4032, Hungary.
| | - János Szöllősi
- Department of Biophysics and Cell Biology, University of Debrecen, Egyetem tér 1, Nagyerdei Krt. 98, Debrecen 4032, Hungary.
- MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Egyetem tér 1, Debrecen 4032, Hungary.
| |
Collapse
|
15
|
Harris MA, Parkes-Loach PS, Springer JW, Jiang J, Martin EC, Qian P, Jiao J, Niedzwiedzki DM, Kirmaier C, Olsen JD, Bocian DF, Holten D, Hunter CN, Lindsey JS, Loach PA. Integration of multiple chromophores with native photosynthetic antennas to enhance solar energy capture and delivery. Chem Sci 2013. [DOI: 10.1039/c3sc51518d] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
|